In the semiconductor industry, it is known that growing a III-N material, such as GaN, on a silicon substrate is difficult due in large part to the large crystal lattice mismatch (−16.9%) and the thermal mismatch (53%) between silicon and GaN. Also, final tensile stress arises during III-N growth on silicon and subsequent cooling of the structure. Thus, some type of buffer layer or layers is generally formed on the silicon substrate and the III-N material is grown on the buffer layer. Generally, the prior art buffer layers, such as an AlN buffer, do no adequately reduce the strain in the silicon substrate or the III-N due to crystal lattice mismatch. Further, during the growth of the III-N material, and especially GaN, diffusion of silicon occurs from the silicon substrate through the AlN buffer and into the III-N material.
It has been found that rare earth nitrides (REN) possess semiconducting and ferromagnetic properties which makes them useful for a large variety of electronic devices. However, there are no free-standing REN substrates. Epitaxial growth on Si is one of the low cost options but the lattice mismatch between Si and REN is several percent (e.g. the mismatch between Si and ErN is a −10.85%). Additionally, the formation of silicide may take place during attempts to grow REN on a Si substrate particularly at the initial stage of the growth.
It would be highly advantageous, therefore, to remedy the foregoing and other deficiencies inherent in the prior art.
Accordingly, it is an object of the present invention to provide new and improved methods for the growth of single crystal III-N material on a silicon substrate.
It is another object of the present invention to provide new and improved methods for the growth of single crystal REN material on a silicon substrate.
It is another object of the present invention to provide new and improved methods for the growth of single crystal III-N material on a silicon substrate using an improved buffer.
It is another object of the present invention to provide new and improved methods for the growth of single crystal REN material on a silicon substrate using an improved buffer.